Project Summary/Abstract The prevention of substance use and misuse among adolescents is a national public health priority. Universal prevention programs that include parents/guardians (referred to as ?parents?) in this effort have been proven efficacious in preventing and reducing substance use problems among adolescents. However, the programs that have been most effective are resource and participant intensive. In addition, the majority of the current programs are not gender-specific and in some cases, long-term effects have been shown for one gender but not the other. The purpose of the current study is to test the efficacy of a brief, communication- based, substance use preventive intervention for parents of pre/early adolescents. The proposal is based on data from a NIDA-funded study where we conducted a pilot randomized controlled trial (RCT) of the intervention among 70 parents/guardians and their children. The intervention was found to be acceptable and feasible to participants and preliminarily efficacious at increasing parent-child communication about substance misuse. The purpose of the pilot study was to lay the groundwork for a fully powered efficacy trial of the intervention, which we are now proposing with 500 parent-child dyads. The brief intervention framework utilizes a one-time in-person session and a follow-up phone call with a communication specialist to facilitate parents' roles as preventionists, which will focus on family interactions at meals, the role of peers in substance use, and parent-child communication about substance use. A particularly innovative component is a focus on eating meals together as a primary intervention strategy to facilitate communication. For the in-person session, parents will be asked to review a handbook with gender-specific information that also emphasizes engaging in family meals, communication, and talking with their child about the harms of substance use. For the home- based component, tips and reminders with content from the handbooks will be sent via text messages through- out the three-month study period. Parents in the comparison condition will receive a handbook, similar in length and structure, on nutrition and physical activity, as well as receive comparison text messages. Framed within the context of the Ecodevelopmental Theory, we hypothesize that over the study period, parents randomized to the intervention will have an increased frequency of parent-child communication about substance use. We also hypothesize that these parents will have more positive and fewer negative family interactions during meals and qualitatively better content of conversations about substance use with their children compared to parents in the comparison condition. Furthermore, we hypothesize that compared to children of parents in the comparison condition, children of parents who receive the intervention will self-report reduced intentions and willingness to use substances, reduced affiliation with substance-using peers, and increased negative attitudes and expectancies regarding substance use, and secondarily, lower rates of substance use initiation. Ultimately, this work addresses the major goal of reducing rates of adolescent substance use and misuse put forth by NIDA.